This invention relates to a ceramic with anisotropic heat conduction and, in particular, to such a ceramic consisting of an aluminum-nitride-based (AlN-based) sintered body and a layer of a polytype of aluminum nitride.
AlN-based sintered body has excellent heat, corrosion and heat-shock resistance, as well as thermal conductivity, so it is used as material for high temperature applications. One of these uses is as a heat conductive substrate in a semiconductor device, as is disclosed in Thermal Conductivity of Commercial Aluminum Nitrode. Ceramic Bulletin, Vol. 51, No. 11 (1972).